Green and efficient method for the iodination of phenols in water

Article abstract of DOI:10.1080/15533174.2011.555856

In this article, green conversion of phenols to the corresponding iodide derivatives is reported. The reactions were conducted in water, using potassium iodide as the source of iodine and potassium ferrate as the oxidizing agent. The selected phenols were successfully iodinated in good to excellent yields in mild and non-toxic reaction conditions. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/15533174.2011.555856

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Synthesis and Reactivity in Inorganic, Metal-Organic,
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Green and Efficient Method for the Iodination of
Phenols in Water
Hassan Tajik a b , Akbar Dadras a & Abolfazl Hosseini c
a Department of Chemistry, University of Guilan, Rasht, I. R. Iran
b Department of Chemistry, Persian Gulf University, Boushehr, I. R. Iran
c Departmentof Chemistry, Islamic Azad University, Qaemshahr, I. R. Iran
Published online: 12 Apr 2011.
To cite this article: Hassan Tajik , Akbar Dadras & Abolfazl Hosseini (2011) Green and Efficient Method for the Iodination
of Phenols in Water, Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 41:3, 258-261
To link to this article: http://dx.doi.org/10.1080/15533174.2011.555856
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Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 41:258–261, 2011
Copyright © Taylor & Francis Group, LLC
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2011.555856
Green and Efficient Method for the Iodination of Phenols
in Water
Hassan Tajik,1,2 Akbar Dadras,1 and Abolfazl Hosseini3
1Department of Chemistry, University of Guilan, Rasht, I. R. Iran
2Department of Chemistry, Persian Gulf University, Boushehr, I. R. Iran
3Departmentof Chemistry, Islamic Azad University, Qaemshahr, I. R. Iran
environmentally safe protocols and green chemistry has attained
the status of a major scientific discipline and organic reactions in
aqueous media and attracted much attention. Water as a green
solvent has attracted organic chemists not only because wa-
ter is one of the most abundant, cheapest, and environmentally
friendly solvents, but also because water exhibits unique reactiv-
ity, rate enhancements, and selectivity improvements different
from the conventional organic solvents.[7−12]
In this article, green conversion of phenols to the corresponding
iodide derivatives is reported. The reactions were conducted in wa-
ter, using potassium iodide as the source of iodine and potassium
ferrate as the oxidizing agent. The selected phenols were success-
fully iodinated in good to excellent yields in mild and non-toxic
reaction conditions.
Keywords green chemistry, iodination, potassium ferrate
Fe(VI) in the form of potassium ferrate[13] (K2FeO4) is
a promising oxidizing agent among other oxidizing metal
salts that exhibits excellent activity for oxidation of organic
substrates[14] and acts as an oxidant in wastewater treatment.[15]
Moreover, this reagent is safe, easy to handle, and environmen-
tally benign.
INTRODUCTION
Iodination of aromatic compounds has received significant
attention in recent years[1] owing to the increasing commercial
importance of iodosubstituted compounds in organic synthesis.
Among them, iodophenols have been valuable intermediates
in the synthesis of pharmaceuticals,[2] natural products,[3] and EXPERIMENTAL
in carbon-carbon bond formation via cross-coupling reactions
General Procedure for the Iodination of Phenols
such as Suzuki–Miyaura,[4] Heck,[5] and Sonogashira.[6]
To a solution of aqueous sodium hydroxide (10 mL, pH 9–
10), potassium iodide (1 mmol) and phenol (1.0 mmol) were
added and the mixture was stirred at 0–5◦C for 20 min. Potas-
sium ferrate (2 mmol) was added portion wise during 10 min,
and the reaction mixture was stirred further at room tempera-
ture for the appropriate amount of time (2–7 h). The progress of
the reactions was monitored by TLC. After completion of the
reaction, the resulting mixture was quenched by the addition
of normal hydrochloric acid and then extracted with ethyl ac-
etate (3×25 mL). The combined organic extracts were washed
with dilute sodium thiosulphate (5%, 10mL), water, and dried
over anhydrous sodium sulphate and concentrated under re-
duced pressure. Further purification was carried out by crystal-
lization from cold hexane or column chromatography.
Numerous methods for the iodination of phenols have
been reported in the literature ranging from IBX-I2,
p-toluenesulfonic acid-NIS, ICl, sodium peroxodisulfate-
I2, NaClO2/NaI/HCl, I2-tetrabutylammonium peroxydisul-
fate, bis(sym-collidine)iodine(I) hexafluorophosphate, ben-
zyltrimethylammonium dichloroiodate, chloramine T-NaI, and
NaI-tert-butyl hypochlorite. However, despite satisfactory re-
sults, most of the reported procedures still suffer from long re-
action times, use of hazardous organic solvents, costly or toxic
reagents and creation of by products and salt wastes which are
not desirable from a green chemistry point of view. Therefore,
according to the mentioned problems and upon the recent strong
attention to environmentally benign protocols, the needs for new
and efficient reagents, and also performing organic reactions un-
der green conditions, there is an area of continuous interest for
the halogenation of organic compounds. Within the past decade,
RESULTS AND DISCUSSION
In continuation of the on-going program on the synthesis of
iodoaromatic compounds,[16] the authors report herein a new
mild and efficient method for the synthesis of iodophenols from
phenol derivatives using K2FeO4/KI (Scheme 1). Based on the
previous results in studying the effect of solvent on the reaction,
Received 21 February 2010; accepted 19 July 2010.
Address correspondence to Hassan Tajik, Department of Chemistry,
University of Guilan, Rasht, I. R. Iran. E-mail: tajik@pgu.ac.ir
258

IODINATION OF PHENOLS IN WATER
259
TABLE 1
Iodination of phenol derivatives with KI/K2FeO4 in water
Yield(%)a
70b
Entry
1
Substrate
Product
Time(h)
OH
OH
4
I
+para
OH
OH
2
3
4
6
3.5
6
80
83
78
CH3
CH3
I
OH
OH
I
CH3
OH
CH3
OH
Cl
Cl
I
OH
OH
5
6
6
2
80
90
I
Cl
O
Cl
OH
OH
O
OH
OH
7
8
3
3
75
76
I
OH
OH
OH
But
tBt
But
tBt
I
OH
9
10
11
5
7
6
82
40
I
Br
Br
OH
OH
I
NO2
OH
NO2
OH
46
I
CHO
CHO
(Continued on next page)

260
H. TAJIK ET AL.
TABLE 1
Iodination of phenol derivatives with KI/K2FeO4 in water (continued)
OH
OH
12
6
52
I
CN
CN
OH
OH
13
14
3
3
75
76
OMe
OMe
I
OH
OH
I
OMe
I
OMe
OH
15
16
3.5
3
72
86
OH
OH
OH
CH3
CH3
I
aIsolated yield; bThe ratio of ortho:para is 30:70
iodination was attempted in water and methanol using 1 mmol quinone rather than undergoing iodination. Mild electron do-
of potassium iodide and 2 mmol of potassium ferrate at 0–5◦C. nating groups, such as alkyl, are also well tolerated. Generally,
It was found that water is the solvent of choice, and moderate phenols with an electron-donating substituent easily underwent
to high conversions and good selectivity for mono-iodination of iodination in shorter reaction time (Table 1, entries 2, 3, 8, 13,
the desired product was afforded.
and 14), in comparison to those substituted with an electron-
According to the obtained results, a variety of phenols were withdrawing group (Table 1, entries 10, 11, and 12). Iodina-
successfully reacted to give the corresponding iodinated prod- tion of moderately electron-deficient phenols also proceeded
ucts (Table 1).
smoothly in good yields (Table 1, entries 4, 5, and 9). In all of
Phenol (Table 1, entry 1) and 1-naphthol (Table 1, entry 7) the reactions, some unreacted starting material was recovered.
gave exclusive iodination at the 4-position; however, 2-naphthol
(Table 1, entry 15) gave 1-iodo-2-naphthol in good yield. Iodi-
nation of 3-methylphenol occurred at the less sterically hindered
4-position (Table1, entry 16). Generally, o-iodination occurred
when the p-position was blocked with a substituent (Table 1,
CONCLUSION
A new eco-friendly methodology for the iodination of phe-
entries 3, 5, 9, 10, 11, 12, and 14). However, 4-hydroxyphenol
nols at 0–5◦C using a non-toxic green reagent (KI/K2FeO4) in
readily oxidized nearly quantitatively to the corresponding p-
water as solvent is reported. Predominantly, mono ortho iodi-
nation occurs in para-substituted phenols, and para-iodination
results with ortho-substituted ones. Further, this reagent works
successfully for the iodination of both electron-activated and
almost deactivated phenols. This method is also effective in
quantitative oxidation of 1, 4-dihydroxybenzene to the corre-
sponding quinone. Although the literature enumerates a number
of reagents for the iodination of phenols, the simplicity, environ-
mental acceptability of this reagent makes it a good alternative
for the green iodination of phenol derivatives.
OH
OH
KI/Potassium Ferrate
X
I
X
Water
X=H, CH3, Cl, Br, OH, t-butyl, NO2, CHO, CN, OCH3
SCH. 1.

IODINATION OF PHENOLS IN WATER
261
REFERENCES
10. Firouzabadi, H.; Iranpoor, N.; Shiri, M. Direct and regioselective iodina-
tion and bromination of benzene, naphthalene and other activated aromatic
compounds using iodine and bromine or their sodium salts in the pres-
ence of the Fe(NO3)3·1.5N2O4/charcoal system. Tetrahedron Lett. 2003, 44,
8781.
11. Firouzabadi, H.; Iranpoor, N.; Kazemi, S.; Ghaderi, A.; Garzan A.
Highly efficient halogenation of organic compounds with halides cat-
alyzed by cerium(III) chloride heptahydrate using hydrogen perox-
ide as the terminal oxidant in water. Adv. Synth. Catal. 2009, 351,
1925.
1. Stavber, S.; Jereb, M.; Zupan, M. Electrophilic iodination of organic com-
pounds using elemental iodine or iodides. Synthesis 2008, 10, 1487–1513.
2. Deagostino, A.; Farina, V.; Prandi, C.; Zavattaro, C.; Venturello, P. New
metal-catalyzed synthesis of quinoline and chromene skeletons. Eur. J.
Org. Chem. 2006, 3451–3456.
3. Bianco, A.; Cavarischia, C.; Farina, A.; Guiso, M.; Marra, C. A new synthe-
sis of flavonoids via Heck reaction. Tetrahedron Lett. 2003, 44, 9107–9109.
4. Sakurai, H.; Tsukuda, T.; Hirao, T. Pd/C as a Reusable catalyst for the
coupling reaction of halophenols and arylboronic acids in aqueous media.
J. Org. Chem. 2002, 67, 2721–2722.
5. Sant’Ana, D.P.; Pinho, V.D.; Maior, M.C.L.S.; Costa, P.R.R. Synthesis of 5-
deoxypterocarpens, pterocarpens, and coumestans by intramolecular heck
reaction. Tetrahedron Lett, 2009, 50, 3753–3755.
12. Lichtenthaler, F.W. In: Methods and Reagents for Green Chemistry: An
Introduction; Tundo, P., Perosa, A., and Zecchini, F. (Eds.); John Wiley and
Sons, Inc.: New York, 2007.
13. Li, C.; Li, X.Z.; Graham, N.
A
study of the preparation
and reactivity of potassium ferrate. Chemosphere 2005, 61, 537–
543.
14. Delaude, L.; Laszlo, P.; Lehance, P. Oxidation of organic substrates with
potassium ferrate (VI) in the presence of the K10 montmorillonite. Tetra-
hedron Lett. 1995, 36, 8505–8508.
15. On-line production of ferrate with an electrochemical method and its po-
tential application for wastewater treatment - a review. J. Environ. Manage.
2009, 90, 1350–1356.
16. Tajik, H.; Mohammadpoor-Baltork, I.; Rasht-Abadi, H.R. Selective para-
iodination of methoxyarenes, phenols, and anilinies with iodine in the pres-
ence of poly(4-vinylpyridine)supported peroxodisulfate. Synth. Commun.
2004, 34, 3579–3585.
6. Pal, M.; Subramanian, V.; Yeleswarapu, K.R. Pd/C mediated synthesis of 2-
substituted benzo[b]furans/nitrobenzo[b]furans in water. Tetrahedron Lett.
2003, 44, 8221–8225.
7. Moorthy, J.N.; Senapati, K.; Kumar, S. ibx−i2 redox couple for facile
generation of IOH and I+: expedient protocol for iodohydroxylation of
olefins and iodination of aromatics. J. Org. Chem. 2009, 74, 6287–6290.
8. Barton, O.G.; Mattay, J. Iodination of activated aromatic compounds using
sodium peroxodisulfate and iodine: an efficient way to iodinate alkylated
calix[4]arenas. Synthesis 2008, 1, 110–114.
9. Firouzabadi, H.; Iranpoor, N.; Kazemi, S. Direct halogenation of organic
compounds with halides using oxone in water – a green protocol. Can. J.
Chem. 2009, 87, 1675.